Fullerenes

ALLOTROPES OF CARBON

1. St. THOMAS COLLEGE, RUABANDHA, BHILAI PRESENTATION TOPIC FULLERENES ( SESSION - 2018) MADE BY - OMPRAKASH PATEL M.Sc. CHEMISTRY(III-SEM .) GUIDED BY - Dr. CHANDA VERMA

2. CONTENTS :- INTRODUCTION A BRIEF HISTORY OF FULLERENE STRUCTURE AND BONDING GEOMETRY OF FULLERENE APPLICATION CONCLUSION REFERENCES

3. introduction:- Fullerenes belong to the carbon family and it is the third allotrope of carbon after graphite and diamond. Fullerenes are closed hollow cage structure consisting of carbon atoms interconnected in pentagonal and hexagonal rings. A fullerene is a pure carbon molecule and C 20 being the smallest fullerene. The most famous fullerene is C 60 also known as Bucky ball .

4. Until the mid-1980s, only two allotropic forms were known, diamond and graphite. But in September 1985 British chemist Sir Harold W. Kroto and the colleagues Richard E. Smalley and Robert F. Curl, Jr., discovered fullerene by using pulsed laser to vaporize graphite rods in an atmosphere of helium gas. The structure of fullerene was suggested to be like a soccer ball: a spherical shape that can be made using 12 pentagons and 20 hexagons. A BRIEF HISTORY OF FULLRENE

5. C 60 was named buckminsterfullerene in honour of Buckminster Fuller. The shortened name 'fullerene‘ is used to refer to the family of fullerenes. In 1996 Curl, Kroto and Smalley was awarded the Nobel Prize in chemistry to for their discovery of fullerenes.

6. STRUCTURE AND BONDING:- C 60 It contains 12 pentagons are surrounded by 20 hexagons. 60 vertices for the carbon atoms and 90 covalent bonds between them, 60 single bonds and 30 double bonds. Each carbon is part of one pentagon and two hexagons, each has two single bonds and one double bond for the traditional carbon valence of four.

7. The fullerene hybridization is not fixed but has variable characteristics depending on the number of carbon atoms in the molecule. The pentagonal rings contain only single bonds; double bonds have a shorter bond length and lead to instability in the pentagonal ring. Two types of bond lengths: (I) 0.145 +/-0.0015 nm for the bonds between five- and six-membered rings, (II) 0.140 +/- 0.0015 nm for the bond between the six-membered rings.

8. GEOMETRY OF FULLERENES:- The geometry of C 60 is icosahedron with sixty vertices, one carbon at each. There are 32 faces, 12 of which are pentagons (12 pentagons × 5 carbons = 60 carbons ) and 20 which are hexagons (20 hexagons × 6 = 120, 120/2= 60 carbons ) we must divide by two because each carbon atom is shared by two hexagons in C 60 . Each pentagon is surrounded by five hexagons. No two pentagons are adjacent.

9. Fullerene must have 12 five-membered faces but the no. of six-membered faces can vary widely. The structure of C 60 has 20 hexagonal faces; C 70 has 25. Each carbon of a fullerene is sp2-hybridised and forms sigma bonds to three other carbon atoms. Fullerenes are aromatic and highly stable.

10. Fullerene family The Fullerene family is ever growing and new added in very large number. The other important parent fullerene is carbon-70 which co-exist with C 60 . it has elliptical shape like rugby ball. It is reddish brown solid whose thicker films are greenish black and it gives wine-red coloured solution in benzene. The other family members are “Bucky babies” include C 32 , C 44 , C 50 and C 58 and the “giant fullerenes” include C 240 , C 540 and C 960 . These giant size fullerene structures have been predicted on the basis of computer simulation of nucleation process model.

11. applications As antioxidants Antimicrobial-agents Drug delivery In solar cells In strengthening/hardening of metals As molecular wires In water purification and biohazard protection As catalyst As sensors.

12. Thus this study gives the basic knowledge of structure of fullerenes and their applications. Fullerenes, have become important molecules in science and technology. Due to their very practical properties, fullerenes are a key topic on nanotechnology and industrial research nowadays. Fullerenes are used in today’s industry already, mostly in and in drug industry and in cosmetics, where they play an important role as antioxidants. conclusion

13. REFERENCES BOOK REFERRED- ADVANCED ORGANIC CHEMISTRY BY DR. Jagdamba Singh & Dr. L.D.S. Yadav, Pragati prakashan, Thirteenth Edition 2016, Page no. 63-65. internet web address - https://www.britannica.com/science/fullerene https://en.wikipedia.org/wiki/Fullerene